Electronic devices predominately have a single printed circuit board from which device functions are performed. In the case of devices having more than two printed circuit boards, modular technology is used with regard to the structure of the printed circuit board. Modular technology is preferably used in cases when the circuits and/or components in the electronic device place different requirements on the printed circuit board. The term “circuits” encompasses circuit components, circuit elements such as conductive track structures, etc., and/or circuit wiring between the circuit components, or between the circuit components or circuit elements and the structural elements.
As an example, in a high-frequency (HF) device including electronic HF circuits and HF components as well as low frequency (LF) circuits and LF components, the LF circuits and components may, for economic reasons, be integrated on a printed circuit board which, unlike the printed circuit board for the HF circuits and components, needs to meet lower requirements with respect to circuit board quality because of the less critical physical characteristics of the LF circuits and components. Accordingly, the printed circuit board with the HF circuits and components will typically appear as a multilayer (e.g., FR4) printed circuit board, whereas the printed circuit board with the LF circuits and components will typically appear as a different multilayer printed circuit board (e.g., FR2, FR3).
To minimize the electromagnetic radiation into and from the HF circuits and components on the FR4 printed circuit board module, in addition to the improved printed circuit board material for the HF module, a shielding element is used that shields the EMI-sensitive electronic components and/or circuits themselves or the entire FR4 printed circuit board module.
To shield electronic components and/or circuits susceptible to Electro-Magnetic Interference (EMI)—such as high-frequency (HF) components and/or high-frequency (HF) circuits used in radio transmitting/receiving devices metal and/or ceramic shielding elements, which shield the EMI-endangered electronic components and/or circuits themselves or the entire printed circuit board, are additionally placed on the printed circuit board of the EMI-sensitive electronic components and/or circuits; to shield the EMI-sensitive electronic components and/or circuits themselves, or the entire printed circuit board.
Examples, of shielding housings or shielding devices are disclosed in U.S. Pat. No. 5,895,884, EP 0 886 464 A2, EP 0 735 811 A2 and DE 199 45 427 C1, and are incorporated by reference in their entirety herein.
In the case of cordless telephones it is known, for example, to provide or configure the housing as a whole, or the frame or lid of the housing, with shielding elements, or to cover the HF components and/or HF circuits with cup- or pot-shaped metal shielding elements.
It is also known in the prior art to shield HF components and/or HF circuits with resistance pastes and so-called Gore foils, the Gore foils generally being used to shield capacitors.
With the known shieldings for high-frequency electrical components and/or circuits, the use of additional shielding elements is disadvantageous because, firstly, additional manufacturing and assembly steps are required and, secondly, the space requirement of the high-frequency electrical components and/or circuits is increased by shielding configured in this way.
Accordingly, there is a need to provide shielding for EMI-sensitive electronic components and/or circuits of electronic devices, in particular for radio transmitting devices and/or radio receiving devices of telecommunication terminal devices for wireless telecommunication, such as cordless and mobile telephones and the like, that can be manufactured without complex and expensive manufacturing and assembly operations and without an additional space requirement.